The F(ab) fragment is part of an antibody that is still capable to bind to its specific antigens and is monovalent with no Fc portion. The enzyme Papain is able to digest an antibody into two F(ab) fragments of about 50 kDa each and one Fc fragment.
Contrary, F(ab')2 fragment antibodies can be generated by pepsin digestion of whole IgG antibodies in order to cleave most of the Fc region without removing the hinge region. F(ab')2 fragments consist of two antigen-binding F(ab) portions which are linked together by disulfide bonds. These fragments are divalent with a molecular weight of about 110 kDa.
Already F(ab) fragment related drugs include Digoxin immune fab (Digibind®, GlaxoSmithKline and DigiFab from BTG plc) as an antidote for an overdose of digoxin. These fab fragments are generated from immunoglobulins of sheep immunized with a digotoxin derivate.
Analytical support for F(ab) fragment development
Protagen Protein Services (PPS) has extensive experience in analysis of different antibody formats and can successfully support you with:
- Developability assessment of candidates
- Detailed Structural Characterization
- Development, Qualification up to Validation of specific analytical methods
- Stability Testing
- Release Testing
PPS provides individual analyses or a comprehensive characterization package customised to suit your requirements and to provide data required by the regulatory authorities for antibody analysis like:
- Determination by intact mass analysis
- Purity and integrity analysis by CE-SDS and cIEF analysis
- Identification by peptide mapping mass spectrometry
- Assessment of quantity by amino acid analysis and liquid chromatography (HIC, RP-HPLC, IEX)
- Aggregation analysis by SEC-MALLS and Analytical Ultracentrifugation (AUC)
- Glycosylation analysis by mass spectrometry, HILIC-FL and HPAEC-PAD
- Mass spectrometric assessment of free thiol groups and disulfide bridges
- Determination of molar extinction coefficient
- Specific functional and potency assays on request